Multimodal sensory testing of the rectum and rectosigmoid: development and reproducibility of a new method.

Evaluation of rectal and rectosigmoid sensation is important in basic, clinical and pharmacological studies. New methods to evoke and assess multimodal (electrical, thermal and mechanical) experimental pain of the upper gut activate distinct pathways and mimics clinical pain. The aims of the current study were to characterize the sensory response and reproducibility to multimodal stimulation of rectum and the rectosigmoid. A multimodal rectal probe was developed. Mucosal electrostimulation was delivered at the recto-sigmoid junction. In Rectum, impedance planimetry was used for measurement of cross-sectional area (CSA) during distension. Circulation of water within the bag at either 4 or 60 degrees C was applied for thermal stimulation. The method was tested in 12 healthy volunteers (six men mean age 32 years) on two subsequent days. Mechanical and sensory responses and referred pain areas were assessed. Stimulation with electrical, thermal and mechanical modalities resulted in different sensory perceptions. The relationship between stimulus intensity and sensory response was linear for all modalities. Sensory response to different modalities did not differ between investigation days (all P-values > 0.1). Approximately 75% of subjects felt referred pain in distinct skin locations. Between-days reproducibility was good for all modalities [intra-class correlation (ICC) > or = 0.6]. At sensory threshold, CSA showed best reproducibility (ICC > or = 0.9). At pain detection threshold stretch ratio, CSA and electrostimulation showed best reproducibility (ICC = 1.0; 0.9; 0.9). The present model was easily implemented, robust and showed good reproducibility. It can be used to study pathophysiology or pharmacological interventions in healthy controls and in patients with diseases involving the distal hindgut.

Colonic pacing in the treatment of patients with irritable bowel syndrome: technique and results.

The treatment of the irritable bowel syndrome (IBS) is not entirely satisfactory as the exact cause of the condition has not been revealed. We have demonstrated in a recent study that the IBS exhibited a "tachyarrhythmic" electromyographic pattern; the wave rhythm was irregular and wave variables were higher than those of the healthy volunteers. We suggested that a disorder of the colonic pacemaker discharges these abnormal waves thereby causing the motor disorders of IBS. In another study, we determined the colonic pacing parameters needed to modulate the disordered pacemaker. In the current communication we investigated the effect of colonic pacing, using these parameters, on the EMG activity of the sigmoid colon (SC) and on the clinical manifestations of patients with IBS. A pacemaker was implanted in a subcutaneous pocket in the inguinal area and its two leads were hooked to the colosigmoid junction. The effect of colonic pacing on the SC EMG activity was investigated by inserting two recording electrodes into the SC muscle. The patients were then trained for home pacing after removal of the 2 recording electrodes. Nine patients (age 42.7 +/- 4.2 years, 6 women) with IBS were studied. The pre-pacing tachyarrhythmic pattern of EMG was recorded. On colonic pacing, the slow wave rhythm became regular and wave variables were normalized; the symptoms of the IBS improved. The optimal parameters used for pacing comprised an amplitude of 6 mA, a pulse width of 150 ms and a frequency of 25% higher than that of the basal colonic waves. In 7/9 patients the improvement of symptoms continued when pacing was ceased after 6 months of daily pacing; the pacemaker was removed after 3 months of non-pacing. In 2/9 patients, pacing needed to be continued because the symptoms recurred each time the pacing was ceased. In conclusion, colonic pacing succeeded in normalizing the tachyarrhythmic pattern and relieving the symptoms of the IBS. No complications were encountered and the method was well accepted and tolerated. Further studies on a large group of patients are required.

Altered periodic rectal motor activity: a mechanism for slow transit constipation.

The pathophysiology of slow transit constipation is poorly understood. Both decreased and increased distal colonic motility have been reported. In healthy humans, a 3 cycles per minute (cpm), periodic rectal motor activity (PRMA) has been described. Our aim was to investigate the characteristics of PRMA and to assess its role in the pathogenesis of constipation. A six-sensor solid-state probe was placed with the tip sensor in the mid-transverse colon, without sedation, and prolonged colonic motility was recorded in nine patients with slow transit constipation (1M, 8F) and in 11 healthy subjects (3M, 8F). Subjects were free to ambulate. We examined the frequency, nocturnal vs. diurnal variation, and characteristics of PRMA, and its relationship to proximal colonic motility. All subjects showed PRMA. The rhythm was similar (2.5-4 cpm) in both groups. However, constipated patients exhibited a greater (P < 0.001) number of PRMA cycles than controls. The duration of each cycle and amplitude of pressure waves during PRMA were also greater (P < 0.05) at night in patients compared with controls. In patients, 40% of PRMA cycles were associated with a proximal colonic motor event compared with 81% in controls (P < 0.02). The area under the curve of all colonic pressure waves and incidence of specialized propagating pressure waves was lower (P < 0.05) in patients during daytime. When compared with controls, constipated patients exhibited reduced daytime colonic pressure waves and a higher frequency of PRMA. Most of the PRMA was unrelated to proximal colonic activity in constipated patients in contrast with findings in control patients. In addition to decreased colonic motility, this excessive and unco-ordinated phasic rectal activity may further impede stool transport and contribute to the pathogenesis of slow transit constipation.

Effect of sigmoid colon distension on the rectosigmoid junction. Description of the rectosigmoid junction tightening reflex and its clinical implications.

PURPOSE: The sigmoid colon (SC) is the site of stool storage. The stools accumulate in the SC until, at a certain volume, the mechanoreceptors in the SC wall are stimulated, evoking the sigmoidorectal junction inhibitory reflex with a resulting SC contraction, rectosigmoid junction (RSJ) relaxation and passage of the stools to the rectum. However, the RSJ status during stool accumulation in the SC has been scarcely addressed in the literature. The current study investigated this point. METHODS: A balloon-ended tube was introduced into the SC of 21 healthy volunteers [mean age (+/- SD) 36.8 +/- 10.3 years; 15 men and 6 women]. The pressures in the SC and RSJ were measured by means of a perfused tube, at rest and during balloon inflation with carbon dioxide at two rates: slow (3 ml/min) and rapid (150 ml/min). The tests were repeated after individual anesthetization of the SC and RSJ. RESULTS: During slow SC distension up to 80 ml included, the RSJ pressure progressively increased while the SC exhibited no pressure response (p > 0.05). At a distending volume of 100 ml, the pressure in the SC rose (p < 0. 01) and declined in the RSJ (p < 0.05), and the balloon was dispelled to the rectum. Rapid SC distension up to 40 ml included, effected no SC pressure response (p > 0.05) while the RSJ showed progressive pressure elevation. At 60 ml distension, the SC recorded a pressure rise (p < 0.001) and the RSJ a pressure decrease (p < 0. 05); the balloon was dispelled to the rectum. The pressure in the RSJ did not respond to distension of the anesthetized SC. CONCLUSION: The study has shown that, during accumulation of stools in the SC, leakage to the rectum seems to be prevented by a reflex action which we call 'rectosigmoid junction tightening reflex'. This reflex probably acts to control both storage and emptying of the SC contents. Reflex dysfunction might lead to defecation disorders. We suggest that the RSJ tightening reflex be included as an investigative tool in the diagnosis of defecation disorders.

A study of the effect of distension of the rectosigmoid junction on the rectum and anal canal with evidence of a rectosigmoid-rectal reflex.

PURPOSE: To elucidate the role of the rectosigmoid junction (RSJ) in the mechanism of defecation. METHOD: Fourteen healthy volunteers were enrolled in the study (10 men, 4 women; mean age 38.2 +/- 10.6 years). The pressures in the rectum, anal canal, and RSJ as well as rectal balloon expulsion were recorded in response to balloon distension of the RSJ in increments of 10 ml of carbon dioxide (CO2) to 50 ml. The experiments were repeated after individual anesthetization of the RSJ, rectum, and anal canal. The expulsion of a 50-ml distended balloon located in the anesthetized rectum was tested. RESULTS: RSJ distension with 10 ml of CO2 produced no significant pressure changes in the RSJ, rectum, or anal canal. A 20-ml distension effected a significant pressure rise in the RSJ (P < 0.05) and the rectum (P < 0.01) and a decline in the anal canal (P < 0.05); the rectal balloon was expelled to the exterior. Similar pressure changes (P > 0.05) were recorded with a 30-, 40-, and 50-ml balloon distension. The mean latency for the RSJ response was 12.6 +/- 2.2 ms and for the rectum 15.8 +/- 2.6 ms. The balloon, distended with 50 ml of CO2 and located in the rectum, was not expelled to the exterior. Balloon expulsion occurred only with distension with volumes of above 80 ml. Individual anesthetization of the RSJ, rectum, and anal canal followed by RSJ distension produced no significant pressure changes in RSJ, rectum, and anal canal as well as no rectal balloon expulsion. CONCLUSION: The rectal contraction upon RSJ distension affirms the hypothesis of the possible involvement of a reflex, which we term "rectosigmoid-rectal reflex." This reflex relationship is evidenced by reproducibility and its absence on anesthetization of either the RSJ or the rectum, both presumably representing the two arms of the reflex arc. It is postulated that stools passing from the sigmoid colon to the rectum distend the RSJ and evoke the rectosigmoid-rectal reflex, which produces rectal contraction. The role of the reflex in defecation disorders needs to be studied.

Rectosigmoid junction: anatomical, histological, and radiological studies with special reference to a sphincteric function.

The existence of a sphincter at the rectosigmoid junction (RSJ) is controversial. Recent studies have demonstrated a high-pressure zone within the RSJ which responds to sigmoid colon or rectal contractions by relaxation or contraction, respectively. These findings suggest the presence of a "physiological" sphincter at the RSJ. The current study investigated the anatomical and histological structure and the radiological picture of the RSJ in view of the possible existence of an anatomical sphincter at the RSJ and elucidating its function. The RSJ was studied in 28 cadavers (18 adults and 10 fully mature neonates) by dissection. A histological study of the RSJ was performed in 5 cadavers. Radiological examination using double-contrast barium enema was carried out in 50 healthy volunteers (mean age 44.2+/-14.4 years; 32 men, 18 women). The mucous membrane of the RSJ was found in folds forming a "mucosal rosette" of a mean length of 2.8+/-0.9 cm in adult specimens and 0.7+/-0.2 cm in neonates. The distal end of the mucosal rosette was sharply delineated and in some specimens protruded into the rectal lumen as a small nipple, which was surrounded by a "rectal fornix" on either side. The histological examination of the RSJ showed mucosal foldings with deep crypts surrounded by lymphocytic aggregates and marginated by muscularis mucosa. The circular muscle coat showed gradually increasing thickness towards the rectum. Nerve cells in the submucosa were located at three levels: in the vicinity of the muscularis mucosa, in the middle of the submucosa, and in the proximity of the circular muscle. Radiologically the opening of the sigmoid colon into the RSJ presented as a ring or crescent. Radiological striations representing the mucosal rosette were demonstrated. The RSJ appeared as a narrow contractile segment. The anatomical, histological, and radiological findings thus indicate that the RSJ is a segment which can be identified by its interior rather than outer aspect. The study suggests the presence of an anatomical sphincter at the RSJ which seems to regulate the passage of stools from the sigmoid colon to the rectum.

Sigmoido-rectal junction reflex: role in the defecation mechanism.

The presence of a sphincter at the rectosigmoid junction (RSJ) is debated. This investigation studies the presence or absence of a sphincter and its possible role in sigmoid colon storage and rectal evacuation. Eighteen healthy volunteers (10 males, 8 females) with a mean age of 36.6 +/- 14.8 years (range 21-53) were studied. The pressure response of the sigmoid colon, RSJ, and rectum to sigmoid and rectal distension, respectively, was determined before and after anesthetizing either the sigmoid colon or the rectum. The RSJ length was evaluated by the station pull-through technique. Sigmoid distension with balloon volumes of up to 80.6 +/- 4.4 ml of H2O effected no sigmoid, RSJ or rectal pressure changes (P > 0.05). At a mean sigmoid distension of 88.6 +/- 4.1 ml of H2O, the sigmoid colon showed a significant pressure increase (P < 0.001), a RSJ pressure decrease (P < 0.05), and insignificant pressure changes in the rectum (P > 0.05); the balloon was dispelled into the rectum. Rectal distension of 94.6 +/- 5.8 ml of H2O produced rectal (P < 0.001) and RSJ (P < 0.05) pressure increases. Distension of the anesthetized sigmoid and rectum did not produce pressure changes in the RSJ (P > 0.05). This study demonstrated a high pressure zone at the RSJ of 3.8 +/- 0.7 cm in length. This suggests that the RSJ might act as a functional sphincter. It opens reflexly upon sigmoid contraction, by a reflex we call "rectosigmoid inhibitory reflex," and closes upon rectal contraction, a reflex we call "rectosigmoid excitatory reflex." The former allows the stored feces in the sigmoid colon to pass to the rectum, and the latter reflex prevents stool reflux to the sigmoid upon rectal contraction.

Psychosensory modulation of colonic sensation in the human transverse and sigmoid colon.

BACKGROUND & AIMS: Psychosensory stimulation increases the perception of stimuli in different regions of the human colon. The aim of this study was to determine the perception of pain and gas during distention of two colonic regions in healthy volunteers during stress and relaxation. METHODS: In 22 healthy subjects, phasic distentions of transverse and sigmoid colon were performed using infinitely compliant balloons, and symptoms were measured before and during one of three randomized treatments: sham or active relaxation or mental stress. Anxiety ratings and somatic cold-pain sensitivity were included in a multivariate regression model. RESULTS: Mental stress increased levels of anxiety (P < 0.05) and the sensation of gas (P < 0.01), but not pain (P = NS), during transverse colon distentions and the sensations of gas and pain during sigmoid distentions (P < 0.05). Active relaxation reduced only sensation of gas in the sigmoid colon. Somatic pain sensitivity and pretreatment colonic sensory scores were significantly associated with the sensory scores during treatments. CONCLUSIONS: Psychosensory stimulation increases colonic sensation during short-term distention in two regions of the human colon; relaxation alone exerts a smaller influence on sensations arising in the sigmoid colon.

Effect of coffee on distal colon function.

Ninety nine healthy young volunteers (58 men, 34 women, aged 17-27 years) answered a questionnaire concerning their bowel habit with particular reference to the effects of beverages. Twenty nine per cent (63% women) claimed that coffee induced a desire to defecate. The rectosigmoid motor responses to black, unsweetened coffee were then investigated by multiport manometry in 14 healthy-subjects (12 men, two women, eight of whom claimed coffee caused a desire to defecate (responders). Results revealed an increase in motility index within four minutes after ingestion of both regular and decaffeinated coffee (p less than 0.05) in the eight responders, but not in the six non-responders. The increase in rectosigmoid motility induced by coffee lasted at least 30 minutes. There was no increase in the motility index in any subject after a drink of hot water. These results suggest that drinking coffee can stimulate a motor response of the distal colon in some normal people.

Dihydroergotamine--stimulation of intestinal peristalsis. An experimental and clinical study.

In an experimental study in 15 beagle hounds using strain gauges a significantly increased motility in the small and large intestine after dihydroergotamine was observed. Since this assessment did not provide any information about mucus transport, gastro-intestinal passage time in patient and control groups was determined using radioopaque catheter material. While transit time in the patient group was significantly reduced by 2 x 0.5 mg DHE s.c./day, this effect was not observed in controls. We related the significantly reduced passage time after DHE in the patient group to a normalisation of a functional disturbance of regulation. The action of the drug is seen in the blocking of the stress induced increased sympathetic tone, without the side effects often seen after pure alpha-antagonists of the phentolamine type or the adrenergic guanethidine type neuronal blocking agents. The specific efficacy of DHE as a partial alpha-antagonist is pointed out. For the clinician, postoperative gastro-intestinal atony might be an indication for its use.